The disgraced sprinter, in his rather incongruous new role as anti-doping campaigner, rolled out a petition down the 100 metres straight in support of the #ChooseTheRightTrack campaign.
Johnson beat Carl Lewis in the 1988 Olympic 100m final only to be stripped of the gold medal and his 9.79 seconds world record for testing positive for the steroid Stanozolol. The race has become known as the 'dirtiest race in history'.
He said: "This has been a significant day in my life and the memories have all come flooding back. Twenty-five years ago, I was here as an athlete who cheated, but today I stand here as an anti-doping campaigner and I'm proud to be able to say that.
"For the last month, I've been talking to people in six different countries about the mistakes I made in using performance enhancing drugs and after seeing the reaction of so many young people around the world who have listened to my story, the act of walking out on to this track, supported by thousands of names on an anti-doping petition, is a very emotional experience.
"During our presentations and discussions across the world, I've seen and heard from people who genuinely want sport to be clean and fair. I was once a part of the other side of the story, so this visit is the perfect end to the tour because, now that I'm older and wiser, it brings everything full circle for me as an athlete and as a person."
The Canadian read names from the 100m long petition as it was rolled out along lane six, the lane he ran from in that notorious final.
Johnson also watched a re-run of that race on the big screen.
Johnson's return to South Korea marks the end of a month-long world tour, in conjunction with with sportswear company SKINS, during which signatures for the petition have been collected.
The petition, which calls for three key changes to anti-doping practices, will be presented to the International Olympic Committee at their offices in Lausanne.